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UBC Theses and Dissertations

The effects of genetic manipulation on the stress response and disease resistance of coho salmon Jhingan, Esther


Genetic manipulation is widely used for the improvement of agricultural organisms. However, alterations of the genome could also result in unintentional changes, and could perhaps alter the performance of the organism. Performance traits such as sensitivity to stressors and to pathogens are strongly influenced by genetic information, and could therefore be affected by alterations of the genome. In this thesis, I tested the hypothesis that genetic manipulation alters the stress response and disease resistance of fish. Specifically, the studies examined the effects of the insertion of a growth hormone (GH) gene construct and triploidy on coho salmon (Oncorhynchus kisutch). In this study, the GH transgene did not alter the physiological or cellular stress responses to a sudden heat shock, relative to those of non-transgenic fish. Exposure of the diploid fish to a bacterial pathogen (Vibrio anguillarum) appeared to reveal differences in disease resistance between different transgenic lines. The first filial generation of GH transgenic fish, which were also a more rapidly growing line, appeared to be more susceptible to disease relative to non-transgenic fish. The second filial generation of GH transgenic fish, which were a slower growing transgenic line, were equally or more resistant than the non-transgenic fish. Disease resistance was compromised by triploidy, and presence of the GH transgene in triploid fish did not appear to further modify the triploid's resistance to the pathogen.

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